Machine for manufacturing switches



W. B. ELLWOOD MACHINE FOR MANUFACTURING SWITCHES Aug ll, 1953 2Shd'ets-Sheet 1 Filed Dec. 18, 1948 FIG. I

A T TORNE V Aug. 11, 1953 w. B. ELLWOOD MACHINE FOR MANUFACTURINGSWITCHES 2 Sheets-Shet 2 Filed Dec. 18, 1948 FIG. 5

FIG. 6'

"VI/[N 09 W B. ELLWOOD By J v A 'ORNCV Patented Aug. 11, 1953 UNITEDSTATES PATENT OFFICE MACHINE FOR MANUFACTURING SWITCHES Walter B.Ellwood, New York, N. Y., assignor to Bell Telephone Laboratories,Incorporated, New York, N. Y., a corporation of New York ApplicationDecember 18, 1948, Serial No. 66,084

Claims.

This invention relates generally to means for manufacturing switches,and more specifically the invention relates to apparatus formanufacturing dry reed switches.

Another object of the invention is a machine for manufacturing switcheswhereby a uniform, reproducible gap between the switch electrodes isattained.

Another object of the invention is to reduce the temperature used insealing the switch e1ectrodes to the glass envelope enclosing saidelec-- trodes by using an assembling process which employs a sealingglass of low fusion temperature which bonds the switch electrodes to theglass switch envelope at temperatures below the softening point of saidglass envelope.

The switch shown in the accompanying drawings is also disclosed in mycopending application, Serial No. 319,483, filed November 8, 1952.

There has been difliculty in the past in manu facturing dry reedswitches with a high degree of electrode space gap uniformity. Applicantovercomes this difficulty and attains his objects as enumerated supra bya switch envelope wherein electrodes are placed substantially end to endin a longitudinal manner with respect to each other, and having thecontact ends of said elec trodes beveled in such a fashion that thebeveled surfaces lie in two parallel planes. The gap between said twobeveled contact surfaces is accurately and uniformly determined by theamount of thermal expansion of an element in a temperature responsivejig which holds switches while the electrodes are spaced and the switchenvelope is sealed in a furnace. A belt guide is used to carry a seriesof these switch holding jigs into a temperature controlled furnace wherethe spacing and sealing steps occur.

The invention, the attainment of its objects, and the nature thereof,may be more full understood from the detailed description infra, read inconjunction with the drawings in which:

Fig. 1 shows a front View in section of an assembled switch in anon-operating condition;

Fig. 2 shows a partially broken away top view of the jig Which holds theswitches during the electrode spacing and envelope sealing steps;

Fig. 3 shows a section view of the jig taken through 3-3 of Fig. 2;

Fig. 4 shows a view of a belt guide carrying a plurality of jigsidentical in structure to the ji of Fig. 2 into a furnace where thespacing of the switch electrodes and the sealing of the switch envelopesare accomplished;

Fig. 5 shows a partially broken away side view of the jig of Fig. 2; and

Fig. 6 shows a perspective view of the jig of Fig. 2.

In Fig. 1 the two electrodes 1 and 8 of a complete switch whoseelectrodes are in a non-operated position are enclosed in the tubularglass envelope 9. In an exemplary embodiment electrodes 1 and 8 are madeof a nickel-iron alloy consisting of about fifty-one per cent nickel andforty-nine per cent iron which has very nearly the same coefiicient ofexpansion as that of annular glass seals I0 and II. It is to be noted,however, that any electrical conducting material possessing magneticproperties may be used as electrodes. The contact tips l2 and I3 ofelectrodes 1 and 8, respectively, are plated with a metal assuring hard,long wearing, low resistance contact surfaces. Rhodium is suitablealthough other metals can be employed. Each of the two electrodes 1 and8 has an upset flange l4 and [5 respectively thereon. These upsetflanges center the electrodes in the glass tube during the sealingprocess. They also define the cantilever length and serve as locationstops for the annular glass seals l0 and II. The contact surfaces of theelectrodes are beveled in such a manner that the two surfaces lie inplanes approximately parallel to each other, thus providing for goodcontact when the relay is activated. The annular glass seals l0 and II,which are inserted in envelope 9 before the spacing and sealing stepsoccur, have a very low melting point so as to reduce the furnacetemperature required for sealing. The seals should also have the sameexpansion coefiicient as the glass envelope 9 and the metallicelectrodes 1 and 8, otherwise the seals are apt to crack when subjectedto temperature variations. The melting point of the glass seals shouldbe below the softening point of the glass envelope so that thecylindrical form of the envelope will not be materially changed duringthe sealing step. Glasses having a sufficiently low melting point arenow available on the market. As is represented by the wire I6, theassembled switch is adapted for use in conjunc- 3 tion with a coil orother source of magnetic flux to form an electromagnetic relay.

In Fig. 2 the assembled switches 30 are positioned in the V grooves ofV-block 3] of the jig. Pole pieces ii, l8, !9, HA, HA and ISA, which areconstructed of magnetic material, cooperating with permanent magnets 2'!and 21A constitute two magnetic chucks which grip the electrodes of eachswitch, holding them in a fixed position with respect to frame 29 andend piece 2i as well as the chucks which are permanently afiixed toframe 20 and end piece 2! while the heating, spacing and sealing stepsoccur. As will be seen from Fig. 3, one of the electrodes for eachswitch abuts against pole-piece HA which aids in properly positioningthe electrodes prior to the spacing and sealing of the electrodes in afurnace. In an exemplary embodiment of the invention bimetal washers 22and 22A are placed on support rods 23 and 23A, respectively. aresupported by frame 29 and end piece 21. When the jig is heated in afurnace the bimetal washers expand and the depth of the cone formed bywashers 22 and 22A increases, forcing end piece 2| away from frame 29.noted, however, that other expansion elements may be employed in placeof the bimetal washers. Friction joints are provided between supportrods 23 and 23A and the contacting surfaces of end pieces 2|, whereasthe rods 23 and 23A are permanently fixed to frame 22. These frictionjoints prevent end piece 2| from moving back towards frame 29 when thejig is cooled and the washers return to normal, otherwise the electrodespacing created by the washer expansion .1

would be destroyed. Spring clamp holder 24 is held in place by screws 25and 25A which are inserted in common supports 26 and 26A. Frame 29, endpiece 2|, and support rods 23 and 23A are all made of non-magneticmaterial, otherwise the magnetic lines of force of the chucks will beinterfered with.

Magnets 21 and 21A are composed of magnetic material which will retainits permanent magnet properties to a high degree at temperatures inexcess of 500 C. a material of this type which is suitable is disclosedin Kelsall et al. United States Patent 2,190,667, dated February 20,1940, as containing 29 per cent nickel, 50 per cent iron and 13 per centaluminum; other alloys of suitable properties are also known in theprior art.

Metallic piece 29 must be of non-magnetic material since its primarypurpose is simply to support pole-pieces ll, [8 and 19 without shorting;likewise, metallic piece 28A must be of nonmagnetic material as itsfunctions with respect to pole-pieces HA, WA and HA are identical tothose of metallic piece 28 with respect to polepieces H, 8 and A9. 29A,which are constructed of magnetic material,

are laid on the top of the projecting extremities of the switchelectrodes so as to reduce the reluctance of the magnetic path for themagnetic chucks as is best shown in Fig. 3. vblock 31 is firmlysupported by and fastened to block 32, the combination of which issecured to frame 29. Fastened to spring clamp holder 24 by rivets 34 isa series of spring clamps 33, one for each switch being manufactured.These spring clamps help to hold the glass envelopes in a fixed positionduring the spacing and sealing steps.

In Fig. 4 jigs 35, which hold the switches to be spaced and sealed, arecarried through heater furnace 36 on conveyor belt 31. Regularly spacedSaid rods It is to be 4 Top clamp plates 29 and Z on the conveyor belt3'! are stops 38 designed to hold and position jigs 35 as they passthrough tube 43 and heater furnace 36. The conveyor belt is guided anddriven by pulleys 39, 5? and 58. An idle pulley 4| and spring 49 with aweight 42 attached to said spring 49 is provided to maintain a desiredtension in the conveyor belt. The conveyor belt 31 passes through thestainless cylindrical metal tube 43. Said tube has an extension 44leading to a helium supply or any other type gas with which it isdesired to fill the glass envelopes of the switches. Also attached tometal tube 4.3 are flexible flaps 25, 4E, 47, A8, 49 and 50, preferablymade of a silicone rubber although other suitable heat resistantmaterials impermeable to gases may be used. These flexible flaps help toprevent air contamination of the helium or other gas injected into themetal tube 43. The purpose of injecting this gas into the metal tube 43is to allow the unsealed envelopes of the switches to become filled withthe injected gas by diffusion before the ends of the glass envelope aresealed in heater furnace 36. At both ends of the conveyor belt areplatforms, platform 51 being designated as the entrance platform andplatform 52 as the exit platform. The loaded jigs are manually placed onthe conveyor belt and automatically leave the conveyor belt and restupon exit platform 52.

The method of manufacture will now be described in detail. Each switchis assembled by placing two electrodes having a structure identical tothat of electrodes 1 or 9 in a glass envelope such as envelope 9. Thebeveled surfaces of these electrodes should be forced against oneanother in a manner shown in the broken section 59 of Fig. 3. Annularglass seals such as l9 or II should be inserted through the projectingextremities of the electrodes until they rest on the upset flanges. Theassembled switches are then placed in the jig in a manner which is bestshown in Fig. 6. In particular the assembled switches rest in theV-grooves of block 3!. The electrodes at the same end of each switchshould rest against pole-piece HA as is shown in Fig. 3. The top plates29 and 29A which are constructed of magnetic material rest on top of theprojecting extremities of the electrodes. To make sure the electrodeelements are positioned so that the contact surfaces are touching eachother and each electrode is also in contact with the inner wall of theglass envelope as is shown in the broken section 59, each electrode endexposed by aperture 89 can be tapped lightly. The electrodes are held ina fixed position with respect to frame 28, end piece 2| and the magneticchucks by the forces exerted by the magnetic lines of forces Bl and '62shown in Fig. 3. Positioned as shown in Fig. 1 the glass seals Hi and IIwill melt when subjected to the heat of the furnace and uponcoolingwillform a seal. The jigs are moved from the entrance platform 5|so as to approach the furnace 39 through tube 43, the glass envelopesare filled with helium by diffusion, and by the time the seal is made,the glass envelope contains helium of sufficient purity for usefuloperation of said switch. As the switch is heated the bimetal washers 22and 22A also heat and of course expand, pushing end piece 2! and itsassociated magnetic chuck away from frame 20 and since the magneticchuck is fastened securely to end piece 2|, the electrodes of eachswitch are pulled apart a certain fixed and uniform distance dependingupon the coefficient of expansion of the v bimetal washers and thetemperature to which they are heated. There is a friction surfacebetween support rods 23 and 23A and end piece 2| so that upon cooling,the end piece 21 does not return to its original position, but remainsin the sition it was in d ri he heated p r Th the gap between theelectrodes is a reproducible one since the temperature is controllable.It should be noted here that magnets 21 and 21A should be arranged as topolarity so that the contact ends of the electrodes are of the samemagnetic polarity and thus will repel each other as one is drawn awayfrom the other during the manufacturing process. Thus, the electrodeswill repel each other into continued contact with the inner surface ofthe glass tubes during the entire manufacturing process, insuring auniform, reproducible gap between said electrodes.

It is to be understood that the above description is an exemplaryembodiment of the invention and that other materials, elements, andarrangements may be utilized without departing from the spirit of theinvention or the subjoined claims.

What is claimed is:

1. A machine for manufacturing a switch of the type having a pluralityof contact electrodes comprising a plurality of magnetic chucks to holdthe electrodes of each of said switches, means for holding said magneticchucks in variable spaced relationship, and a heat responsive expansionunit mechanically coupled to said means whereby the magnetic chucksholding said switch electrodes are moved with respect to one another inresponse to heat from a furnace or the like.

2. A machine for manufacturing a switch of the type having at least twospaced electrodes comprising first means for holding one of saidelectrodes, second means for holding another of said electrodes in aninitial position with respect to said one of said electrodes, andthermally-expansible means connected to both of said means forcontrolling the relative positions of said first and said second meansto critically space said electrodes.

3. A machine for manufacturing a switch of the type having at least twospaced electrodes within a sealed envelope, comprising first means forholding one of said electrodes, second means for holding another of saidelectrodes in an initial position with respect to said one of saidelectrodes, means for supporting said envelope, t'hermally-expansiblemeans connected to both of said means for controlling the relativepositions of said first and said second means to critically space saidelectrodes, and means for sealing said electrodes within said envelope.

4. A machine for manufacturing a switch of the type having at least twospaced electrodes within a sealed envelope, comprising first means forholding one of said electrodes, second means for holding another of saidelectrodes in an initial position with respect to said one of saidelectrodes, means for supporting said envelope, thermally-expansiblemeans connected to said first and said second means for controlling therelative positions of said first and said second means to criticallyspace said electrodes, means for filling said envelope with a gas, andmeans for thereafter sealing said electrodes within said envelope.

5. A machine for manufacturing a switch of the type having at least twospaced electrodes within a sealed envelope, comprising first means forholding one of said electrodes, second means 6, for holding another ofsaid electrodes inan initial position with respect to said one of saidelectrodes, means for supporting said envelope, thermally-expansiblemeans connected to said first and said second means and effective uponthe application of heat thereto for controlling the relative positionsof said first and said second means to critically space said electrodes,means for retaining said first and said second means in the latterposition during cooling, and means for sealing said electrodes withinsaid envelope.

6. A machine for manufacturing a switch of the type having at least twospaced electrodes of magnetic material, comprising first magnetic meansfor holding one of said electrodes, second magnetic means for holdinganother of said electrodes in an initial position with respect to saidone of said electrodes, and thermally-expansible means connected to bothof said means for controlling the relative positions of said first andsaid second means to critically space said electrodes, like poles ofsaid magnetic means engaging said electrodes.

'7. A machine for manufacturing a switch of the type having at least twospaced electrodes of magnetic material, comprising a first magnet forholding one of said electrodes, a second magnet for holding another ofsaid electrodes in .an initial position with respect to said one of saidelectrodes, first and second support means individual to and holdingsaid magnets, and means including thermally-expansible meansintermediate and engaging said first and said second support means forcontrolling the relative positions of said first and said second supportmeans thereby moving said electrodes into a critically spaced relation.

8. A machine for manufacturing a switch of the type having at least twospaced electrodes of magnetic material, comprising a first magnet forholding one of said electrodes, a second magnet for holding another ofsaid electrodes in an initial position with respect to said one of saidelectrodes, like poles of said magnets engaging said electrodes, firstand second support means individual to and holding said magnets, andmeans including thermally-expansible means intermediate and engagingsaid first and said second support means for controlling the relativepositions of said first and said second support means thereby movingsaid electrodes into a critically spaced relation.

9. A machine for manufacturing a switch of the type having at least twospaced electrodes of magnetic material in a sealed envelope, comprisinga first magnet for holding one of said electrodes, a second magnet forholding another of said electrodes in an initial position with respectto said one of said electrodes, means for supporting said envelope,first and second support means individual to and holding said magnets,means including thermally-expansible means intermediate and engagingsaid first and said second support means and effective upon theapplication of heat thereto for controlling the relative positions ofsaid first and said second support mean-s thereby moving said electrodesinto a critically spaced relation, means for retaining said first andsaid second support means in position during cooling, and means forsealing said electrodes within said envelope in said critically spacedrelation.

10. A machine for manufacturing a switch of the type having at least twospaced electrodes of magnetic material in a sealed envelope, comprisinga first magnet for holding one of said electrodes, a second magnet forholding another of said electrodes in an initial position with respectto said one of said electrodes, like poles of said magnets engaging saidelectrodes, means for supporting said envelope, first and second supportmeans individual to and holding said magnets, means includingthermally-expansible means intermediate and engaging said first and saidsecond support means and effective upon the application of heat theretofor controlling the relative positions of said first and said secondsupport means thereby moving said electrodes into a critically spacedrelation, means for filling said envelope with a gas, means forretaining said first and said second support means in position duringcooling, and means for sealing said electrodes within said envelope insaid critically spaced relation.

WALTER B. ELLWOOD.

References Cited in the file of this patent UNITED STATES PATENTS

